1. Field of the Invention
The present invention relates to a wrench which has unique pairs of inside working surfaces which are non-parallel to one another and have been developed to reduce or eliminate slippage and other conventional wrench problems, and to provide for surface-to-surface contact instead of point-to-point contact during high torque usage. The present invention wrench may be open-end, adjustable, or otherwise.
2. Information Disclosure Statement
Various types of wrenches having conventional configurations to conform to the exact shape of nuts, bolts and fasteners with which they are used have, by necessity, tolerances and clearances which create problems when substantial torque is applied to the wrenches. Recent developments in the art have been directed to the reduction of slip and wear of fastener corners by conventional wrenches.
For example, U.S. Pat. No. 3,125,910 issued to Kavalar describes a wrench having at least 10 cylindrical lobes for equalizing torque exertion. U.S. Pat. No. 3,241,409 to Raptis describes a box wrench having a pivotally, slidably disposed torquing element for relative movement of opposite contact surfaces within the wrench opening during application of torque. This device requires substantial manufacturing with moving parts.
U.S. Pat. No. 3,242,775 to Hinkle describes a wrench for engaging nut contact surfaces to inhibit marring. Curved wrench surfaces are utilized for contact surfaces of the wrench head, and angles vary along these contact surfaces to have a first, then a second portion contact the nut sequentially with increased torquing.
U.S. Pat. No. 3,695,124 to Myers describes an angular wrench head with arcuated ribs for rounded point contact with fasteners.
U.S. Pat. No. 3,881,377 to Evans et al describes a ratcheting wrench for octagonal or hexagonal members having a body, a handle means attached to the body, a torquing jaw and a backup jaw extending from the body to receive the octagonal or hexagonal member therebetween, the backup jaw has a planar working surface and the torquing jaw having a working surface parallel to and spaced from the working surface of the backup jaw, the length of the torquing jaw working surface being less than one-half the length along a side of the octagonal member, the torquing jaw terminating at the outer end opposite the handle in an inclined slipping surface, the ratcheting wrench serving to engage the octagonal or hexagonal member in successive rotary motion without removing contact from the octagonal member.
U.S. Pat. No. 4,361,412 to Stolarczyk describes a body that is provided defining a center axis and having at least four adjacent sides equally spaced from and about the center axis and disposed normal to adjacent 60.degree. relatively angularly displaced radii of the center axis. Each of the sides includes opposite ends and at least the center two sides of the four adjacent sides are interrupted centrally intermediate their opposite ends by a pair of spaced torque transfer surfaces spaced apart generally one-third the length of the corresponding side and equally from the opposite ends thereof. The surfaces are disposed on radii of the center axis. In a first form of the invention only four of the adjacent sides are provided and the end two or remote sides of the four adjacent sides are free of the aforementioned transverse surfaces and the sides face inwardly toward the center axis of the body. In second and third forms of the invention, the sides equal six in number and comprise outwardly and inwardly facing sides, respectively, and each of the sides includes the side interrupting surfaces with the surfaces extending from the sides inwardly toward the center axis. Each pair of surface inner ends are interconnected by an edge extending therebetween disposed generally normal to a radius of the center axis bisecting the edge.
U.S. Pat. No. 4,512,220 to Barnhill, III et al describes a socket wrench for a hexagonal fastener wherein the clockwise and counterclockwise drive portions of the internal surface configuration of the wrench engage an associated hexagonal fastener with substantially surface to surface contact on each fastener side in close proximity to, but always spaced from, a fastener corner, thereby providing a maximum practical moment arm between wrench and fastener, and yet avoiding deteriorating engagement between the wrench and the fastener corners. The clockwise and counterclockwise drive portions of the wrench occupy the middle about 1/2of each uniform 60.degree. segment of the wrench opening. The space on the internal surface configuration of the wrench between adjacent pairs of drive portions is relieved just enough to avoid interference with the corners of the fastener, thereby providing a rotational clearance of about 25.degree. with the fastener, the precise angular amount depending on manufacturing tolerances in the wrench and fastener. This extended rotational clearance is particularly advantageous in the field of power driven socket wrenches, especially power driven socket wrenches of the multiple spindle type commonly used in manufacturing operations.
U.S. Pat. No. 4,598,616 to Colvin describes a wrench opening is disclosed as having particular utility for use with a socket or closed end wrench and includes inwardly convex engagement surfaces defining a closed shape and having continuously curved end portions that provide greater surface-to-surface engagement with a nut or bolt head to be torqued than is possible with conventional flat engagement surface portions. The curvature of the engagement surfaces is selected to provide maximum surface-to-surface engagement when normal tolerance deviations are involved. Connecting surfaces extending between the engagement surfaces are constructed to provide improved stress distribution and reduced tooling cost.
U.S. Pat. No. 4,882,957 to Wright et al describes a wrench for turning a fastener nut having a central axis and an even-numbered plurality of flat bounding surfaces parallel to the central axis with diametrically opposite pairs being parallel to each other. The wrench includes a fastener nut engaging socket defined about a central socket axis by a plurality of uniformly spaced peripherally and radially disposed protuberances and a plurality of uniformly spaced corner recesses disposed between the protuberances. Each protuberance includes side-by-side angularly related straight engaging surfaces at substantially 142.degree. outside obtuse angles to each other for registry with the flat surfaces on the fastener nut and complementary side surfaces outwardly diverging from said engagement surfaces. Each recess is comprised of a first arcuate surface tangential to a circle about the central axis of the socket and transitional surfaces converging from the side surfaces of adjacent protuberances toward the first arcuate surface.
U.S. Pat. No. 5,131,312 to Macor describes a wrench for tightening and loosening bolts, nuts and fasteners having a number of equal length outside working surfaces. The wrench has a working wrench head with an orifice which contains at least two pairs of flat inside working surfaces. The pairs of inside working surfaces are arranged about and equidistant from an imaginary central axis through the orifice, and the surfaces of each pair form a surface contact angle A with one another. A handle which, is removably or permanently connected to the working wrench head and adapted for rotation of the working wrench head. In one preferred embodiment, two pairs of flat inside working surfaces are directly opposite one another.
Notwithstanding attempts in the prior art to overcome the substantial deficiencies of standard wrenches none of the prior art teaches or renders obvious the improved wrench of the present invention with its non-parallel, specifically defined working surfaces.